Production of naphthalene



June 12, 1956 H. n. COONRADT 2,

PRODUCTIQN 0F NAPHTHALENE 2 Sheets-Sheet 1 Filed Sept. 16, 1952 HYDROGEN 1000? HYDROGEN 20 fl TMOJPf/ERES PRESSURE NITROGEN TEMPER/m/RE, "F

IN V EN TORS Y w M MW m ME 7 n m 1 m m Y B June 12. 1956 H. L. comma EI'AL 2,750,432

PRODUCTION OF NAPHTHALENE (WA 71467 7/ME SEZ'U/l/DS m m D H N r 0 IUDO'E N0 HY ROGEN INVENTORS Z. faonnuii By fiar n United States Patent PRUDUCTIQN OF ITAPHTHALENE Harry L. Coonradt, Woodbury, and Barton W. Rope,

Mullica Hill, N. 1, assignors to Socony Mobil Oil Company, Inn, a corporation of New York Application September 16, 1952, Serial No. 309,928

9 Claims. (Cl. 260-672) groups containing two or more carbon atoms from alkylaromatic compounds. The reaction proceeds easily and in good yields. In direct contrast thereto, however, demethylation, i. e., the removal of the methyl group from a methyl-substituted aromatic compound, has been relatively ditficult to accomplish. Additionally, the yields obtained have been relatively low. In U. S. Patent No. 2,194,449, it has been proposed to effect the demethylation of methylnaphthalenes in the presence of clay type catalysts. The yields of naphthalene, however, were fairly low. This reaction was subjected to further study by Hansford et al., in Ind. Eng. Chem., 37, 671 (1945). Better yields were obtained by the writers when a bead type silica-alumina catalyst was used. The reaction was also investigated by Greensfelder et al., Ind. Eng. Chem., 37, 1168 (1945). In all cases, the highest yields of naphthalene obtainable were in the order of 55-60 per cent, based on the weight of methylnaphthalene charged. It will be appreciated that it is desirable to achieve a process wherein the catalytic production of naphthalene from methylnaphthalenes can be achieved in higher yields.

It has now been found that naphthalene can be produced from methylnaphthalenes by a catalytic process that is relatively simple and which is commercially feasible. It has been discovered that naphthalene can be produced from methylnaphthalenes by a process which involves contacting the methylnaphthalene with a silicaalumina catalyst in the presence of hydrogen gas.

Accordingly, it is an object of the present invention to provide a catalytic process for the production of naphthalene, which is simple and commercially feasible. Another object is to provide an improved catalytic process for the production of naphthalene from methylnaphthalenes. A more specific object is to provide an improved process for producing naphthalene from methylnaphthalenes, in the presence of silica-alumina catalyst and of hydrogen gas. A further object is to provide a method for the hydrogenolysis of methylnaphthalenes to naphthalene in the presence of silica-alumina catalysts. Other objects and advantages of the present invention will become apparent to those skilled in the art, from the following detailed description taken in conjunction with the drawings, in which:

Figure 1 shows two curves representing graphically the relationship between hydrogen pressure and the yield of naphthalene obtained by contacting Z-methylnaphthalene a 1 amounts of materials adapted to improve other character- I tacting the 2-methylnaphthalene with silica-alumina catalyst for a contact time of 10 seconds;

Fig. 3 shows two curves representing graphically the relationship between yield of naphthalene from Z-methylnaphthalene and temperature, when contacting the 2- methylnaphthalene with silica-alumina catalyst, in the presence of hydrogen, at atmospheric pressure, and for contact times of five seconds and 10 seconds; and

Fig. 4 shows a curve representing graphically the rela-. tionship between contact time and the yield of naphthalene obtained by contacting Z-methylnaphthalene with silicaalumina catalyst, at 1000 F. and at 1100 F., in the presence of added hydrogen at atmospheric pressure; and at 1000 F. and 1100 F., at atmospheric pressure, in the absence of added hydrogen.

In general, the present invention provides a process for the demethylation of methylnaphthalenes, which comprises contacting the methylnaphthalene with a silicaalumina catalyst, at a temperature of between about 900 F. and about 1200" F., for a period of time of between n about one second and about seconds, and in the presence of hydrogen gas at substantially atmospheric pressure.

In its broadest aspect, the present invention contemplates the removal of one or more methyl radicals, i. e.,

1 the demethylation, of a methyl-substituted naphthalene by a process of hydrogenolysis in the presence of silicaalumina catalyst. The preferred embodiment thereof, however, relates to the production of naphthalene from monomethylnaphthalenes. Non-limiting examples of the methylnaphthalenes utilizable as charge stocks in the process of the present invention are l-methylnaphthalene; Z-methylnaphthalene; 1,4-dimethylnaphthalene; 2,3-dimethylnaphthalene; 2,7-dimethylnaphthalene; 1,2,3-trimethylnaphthalene; 1,2,5-trirnethylnaphthalene; l-methyl- 4-ethylnaphthalene; tetramethylnaphthalene; l-methyl-7- isopropylnaphthalene; and 1,4-dimethyl-6-ethylnaphthalene. The charge material can be a relatively pure methylnaphthalene, or it can be a mixture of two or more Likewise, the charge stock can be a hydrocarbon fraction which is rich in methylnaphmethylnaphthalenes.

thalenes, such as certain aromatic petroleum fractions.

The catalyst utilizable in the process of this invention is a silica-alumina cracking catalyst. prises between about 5 per cent and about 20 per cent, by weight, of alumina, with the balance, i. e., between about 95 per cent and about 80 per cent, by weight, being silica. Preferably, the catalyst contains between about 8 per cent and about 15 per cent alumina, by Weight. Also, there can be incorporated into the catalysts minute istics of the catalyst. For example, minute amounts, between about 0.05 percent and about 1.0 per cent, by weight, of chromia can be added to the catalyst to assist in after burning properties of the catalyst during regenera- '-'tion. This amount of chromia is not a promoter, since it with silica-alumina catalyst for 10 seconds contact time 2-methylnaphthalene at various temperatures, when com does not afiect the catalytic activity. Such a catalyst is still basically a silica-alumina catalyst with respect to activity. Such catalysts are described in copending application Serial No. 127,626, filed November 16, 1949. The silica-alumina catalyst can be in any usual form in which such catalysts are used, i. e., rods, pellets, spheres, etc. Preferably, however, the catalyst is in the form of spheroidal, bead-like particles, having a particle size of between about 4 and about 12 mesh. Such particles can be prepared, feasibly, in accordance with the method described in United States Letters Patent No. 2,384,946. Reference should be made thereto for the procedures involved.

The process of this invention is carried out in the pres- Ience'of hydrogen gas, or of a gas which is rich in hydro- It ordinarily comgen, such as the gas produced in various reforming operations. The hydrogen gas can be introduced into the reactor along with the methylnaphthalene charge stock, or it can be introduced separately, mixing occurring in the reactor. The molarproporticn of hydrogen to meth-ylnaphthalene can vary between about 1:2, respectively, and about 10:1, respectively, and preferably between about 641-, respectively, and about 2:1, respectively. It has been foundthat a proportion of about 6:1 is especially feasible.

Referring now to the curves shown. in Fig. 1, which are based on dataset forth in the examples, infra, obtained by contacting Z-methylnaphthalene with a silicaalumina bead-form catalyst, for a 10'second contact time, in thepresence of hydrogen, in a, molar proportion of hydrogen to methylnaphthalene of about 6:1, at various temperatures, and under several: pressures, it will be observed: that the yields offnaphthaleneare much higher at atmospheric pressure, at any given temperature. The pressure in thereactor, i. e., the hydrogen gas. pressure, should be maintained; preferably, at about atmospheric pressure, or at subatmospheric pressures. In general, it has been found that as the hydrogen pressure is.increased, the yield of demethylated: methylnaphthalene decreases. Improved yields. of demethylated. products. are obtained. at. pressures uptorabout 5- atmospheres. At. higher'pressures, however, there is little advangtage to be gained. by. the use, of added hydrogen. Superatmospheric; pressures should, be; avoided, as a general rule.

The vastly improved results, obtained by the process of this invention, are; achieved only when hydrogen gas is added. Referring to the curves shown, in Fig. 2-, itis apparent that; the addition of hydrogen effects superior yields of naphthalene. These curvesare based on data. (set. forth hereinafter in the examples} obtained by contacting lntcthylnaphthalene with a bead-form silica alumina catalyst, at various temperatures, for a r-second contact time,- at atmospheric pressure, and (1) in the absence of added gases, (2) in the presence of hydrogen, and (.35) in thepresence-of nitrogen gas; the gases, in each instance, being added in a molar proportion of gas, to methylnaphthalene of about 6:1. Fromv these curves it will be noted that maximum yields of over 70 percent were achieved whenv hydrogen was used, as opposed to maximum yields: of about 60 per cent in the absence of hydrogen. When an inert diluent gas, such as nitrogen, wasused, the yieldwasnot. much improved. In add tlon tothe foregoing, it has been found that hydrocarbons which are often. added, to conversion processes, to decompose to forrnhydrogen, are not effective in the present process. Indeed, hydrogen gas itself, not a hydrogen gas; forming substance or a diluent, is the only substance found. to be effective in the improved process of this invention.

The contact temperature, i. e., the catalyst temperature, and, the contact timeare interdependent. Referring tothecurves shown in Fig. 3, which are based upon data (set forth hereinafter in the examples) obtained by contacting Z-methylnaphthalene with a silica-alumina catalyst, at various temperatures, in the presence of hydrogen under atmospheric pressure and in a molar proportion ofhydrogen to methylriaphthalene of about 6:1, and for contact times of 5 seconds and of 10 seconds, it will be seen thatv excellent yields of naphthalene were obtained at temperatures of between about 900 F. and about 1100 F., with optimum yields at between about 900 F. and about. 1050" F. In general, the present process is found to be operable at temperatures of betweenabout 900 F. and about 1200 F and, preferably, between about 900 F. and about1-100f F. Itwill also be noted that, at higher temperatures, the shorter contact timeproduces optimum ultimateyieldscf naphthalene. The converse hOldS true at lower temperatures. Conversion per pass, on the other,

hand, is highest when a combination of higher temperature'and longer contact time is used. The ultimate yield,

4. however, suffers under these conditions. Thus, the selection of reaction conditions is dependent upon whether greater yield per pass or high ultimate yield is desired. The selection of the conditions to effect the desired result is made in view of the considerations set forth hereinbefore.

The curves shown in Fig. 4 are derived from data obtained by contacting Z-methylnaphthalene with a silicaalumina catalyst, at 1100 F. and at 1000 F., in the presence of hydrogen in a molar proportion of hydrogen to methylnaphthalene of about 6: 1, and in the absence of hydrogen at 1000 F., and 1100 F., and for various contact times. It will be observed therefrom that at 1100' F., when hydrogen is used, the yield of naphthalene falls off as the contact time is increased. At 1000 F., it will be noted, the yields are much higher for the longer contact times than when runs are made at 1100 F. As indicated in Fig. 3, longer contact times can be used at lower temperatures. tained atthese temperatures when no hydrogen was added were much lower than when hydrogen was used. In general, the contact time in the process of this invention can vary withinthe range of between about one second and about 200 seconds, inclusive, dependent, as stated hereinbefore, upon the temperature. It is preferred to operate-for contact times of between about one second and about 2,0 seconds.

Since the temperatures employed in the process of this invention are well above the boiling point of methylnaphthalenes, it will be apparent that the present process involves a vapor phase operation. Any reaction vessel; suitable for carrying out contact catalytic operations can be-used; The reactor should be provided with suitable means for maintaining the catalyst temperature. Contact. between the catalyst and the charge material can be etfectedby passing the charge vapors over or through the catalyst; The catalyst can be in the form of a fixed bed or a moving bed. Theprocess, of course, can be per forrned in a: batch process. It is preferable; however, to employs-continuous operation. In such an operation, the charge is passed through the reactor in contact with the catalyst. Thenthe effluent reaction product is subjected to a productseparationoperation. The portion of thecharge stock which remains undemethylated and/or whichis incompletelydemethylated (as with polymethylnaphthalene charge materials) can be recycled to the reactor, until'the maximum ultimate conversionhas been etfected.

Thefollowing examplesare forthe purposeof demonstrating the process of this invention. and the superior resultseobtained therefrom. It must be-strictly'understoodthat this invention is not to be limited by thereactants and conditionsused in the examples, or by the operations and manipulations involved therein. As will be apparent tothose; skilled intheart, other reactants and conditions, 3.5:.Sfilaf0l1th hereinbefore, can be used to practice this inYfiHflQIh APPARATUS AND OPERATION The reactor used in the runs described in the, exam: ples, was a stainless steel tube suspended in. a bath of molten lead. The temperature of the lead wascontrolled to maintain the catalyst temperature constant to within about; 10 Catalyst temperature was measured by means of thermocouples extending into the top, mid.-

dle,.and bottom. Portions of the catalyst. bed. A total.

volume of about cubic centimeters of catalyst was placed in the reactor. Accessory equipment included a heated, thermostatically controlled burette for measuring the charge, pumps, preheater coils, a condensing and collecting system for aromatic and gaseous products, and a system "ford'eterm-ining the amount of cokeon the catalyst by a combustion method.

In operation, the catalyst, at operating temperature, waspurgedrwith nitrogem gas; followed by aflushingwith hydrogen whenzusedinthc:nun. Then, the; charge mats:

In contrast thereto, the yields ob-- rial, in the liquid state, together with added gases or and results from certain runs set forth in part A thereof, liquids was passed through a 'preheater to raise the ternin order to demonstrate the effect of contact time on the perature thereof to the reaction temperature. The comyields. bined charge was then passed downwardly through the catalyst bed at a rate suflicient to eifect the desired con- 5 EXAMPLES 19 THROUGH 22 tact time. A sample of the total gas collected was ana- A series of runs were made using 2-methylnaphthalyzed in the mass spectrometer to determine its composilene, and the same catalyst as in the preceding examples. tion and the weight of the components. The principal The contact temperature was maintained at 1100 F., component was methane. while the contact times were at about 5 seconds. The

' The amount of coke laid down on the catalyst was de- 10 pertinent data and results for these runs are set forth termined by combustion methods, i. e., by converting it to in the last portion of part B of Table I, along with data carbon dioxide and analyzing therefor. The relative and results from certain runs set forth in part A thereof,

amounts of aromatic materials present in a sample of the in order to demonstrate the effect of contact time at liquid products was determined by usual methods, i. e., 1100 F.

Table I.--Demethylation of methylnaphthalene over silica-alumina bead cracking catalyst Yield of Products, Weight Percent Yield of Products, Ulti- Oharge Stock h Length Methyl- Ocn- Per Pass mate Weight Percent 4 Temp, ot naphthyltact Example R ene 4 Time,

g,/min. 3 23 3 Coke Gas Total $5 232 Coke Gas 48.6 1. 97 950 24 6 0.803 10.1 9. 1 79. 9 6.0 0.8 95. 7 57. 2 37.8 5. 48. 4 2. 950 24. 2 0.812 10.0 7. 9 82. 4 6. 6 0.8 97. 7 51. 7 43. 1 5. 48. 4 2.0 950 24. 2 0.810 10.0 10. 7 76. 2 7. 0 0. 8 94. 8 57. 8 37. 9 4. 48.5 1. 93 1, 600 25.1 0.785 10.0 15.5 72.7 8. 3 1. 2 7. 6 62.0 33. 2 4. 48.3 1. 92 1,000 25. 2 0.779 10.2 14.1 73. 3 7. 7 1. 4 96.5 60.8 33. 2 6. 48. 4 l. 93 1, 009 25. 1 0. 784 10.0 16. 3 71. 5 9. 5 1. 2 98. 5 69. 4 35. 2 4. 48.4 1. 92 l, 000 25. 2 0.779 10. 1 l4. 5 70. 9 8. 9 1. 4 95. 7 58. 5 35. 9 5. 99. 0 1. 93 1, 000 51. 3 0. 800 10.0 13.0 75. 3 6. 8 1. 4 96. 5 61. 3 32.0 6. 98. 6 1. 93 1, 000 51. 1 0. 784 10.0 11.8 79.0 7.0 1.3 99. 7 58. 7 34. 8 6. 48. 4 1. 80 1,100 26.8 0.732 10.0 21.5 58.3 14.2 3. l 97. 1 55. 3 36. 7 8. 48.5 1.81 1,100 26.8 0.735 9. 9 23. 5 53. 8 15. 9 3.1 96.3 55. 3 37. 4 7. 48.7 1. 81 1, 100 26. 7 0. 735 10.0 20.0 57. 2 l5. 5 1. 4 94.2 54. 2 42.0 3. 98. 2 1. 79 1, 100 54. 9 0. 725 10. 1 19.0 61. 7 12. 9 3. 2 96.8 54. 1 36. 8 9. u 48. 5 3. 83 1, 000 12. 6 1. 558 5. 0 11. 4 82. 6 6. 6 0. 8 101. 3 60. 4 35. 2 4. 48. 4 3. 87 1,000 12. 5 1. 57 5. 0 9. 3 81. 8 6. 2 0. 8 98. 1 57. 0 38. 1 4. 48.4 3. 83 1,000 12.6 '1. 56 5.0 9. 5 81. 8 6. 6 0.8 98.7 56. 2 39. 1 4. 97. 7 3. 74 1, 000 26. 2 1. 514 4. 9 8. 1 86. 5 4. 9 0. 7 100. 2 59.0 35. 8 5. 98. 9 3. 76 1, 000 26.3 1. 527 5. 1 10. 4 83. 0 5. 5 0. 8 99. 7 62. 4 32. 7 4. v 48. 5 1. 93 1,000 25. 1 0.785 10.0 15. 5 72. 7 8. 3 1. 2 97. 6 62. 0 33. 2 4. 48.3 1. 92 1, 000 25. 2 0. 779 10. 2 14. 1 73. 7 7. 7 1. 4 96. 5 60.8 33. 2 6. 48. 4 1. 93 1, 000 25. 1 0. 784 10. 0 16. 3 71. 5 9. 5 1. 2 98. 5 60. 4 35. 2 4. 48. 4 1. 92 1, 000 25.2 0.779 10. 1 i 14. 5 70.9 8. 9 1. 4 95. 7 58. 5 35. 9 5. 99.0 1. 93 1, 009 51. 3 0.800 10. 0 13. U 75. 3 6. 8 1. 4 96. 5 61. 3 32.0 6. 98.6 1. 93 1, 009 51. 1 0. 784 10. 0 11. 8 79. O 7. 0 1. 3 99. 7 58. 7 34. 8 6. 48. 5 3. 60 1, 100 13. 5 1. 46 5. 0 14. 2 65. 4 11.8 2. 9 94. 11 49. l 40. 8 10. 48. 5 3. 59 1, 100 13.5 1. 46 5.0 16. 3 68. 5 13. O 2. 3 100. 0 51.. 6 41. t) 7. 48.4 3. 61 1., 100 13. 4 1. 46 5.0 16. 9 67. 8' l0. 9 1. 4 97. 0 57. 9 37. 3 4. 98.8 3. 59 1,100 27. 5 1. 460 5. 0 14.6 72. 3 9. 7 1.7 98. 3 56.0 37.4 6. 48. 4 1.80 1, 100 26.8 0. 732 10.0 21. 5 58. 3 14.2 3. 1 97. 1 55. 3 36. 7 8. 48. 5 1. 81 1, 100 26.8 0. 735 9. 9 23. 5 53. 8 15.9 3. 1 96. 3 55. 3 37. 4 7. 48. 4 l. 81 1, 100 26. 7 0. 735 10. 0 20. 0 57. 2 15. 5 1. 4 94. 2 54. 2 42. 0 3. 98. 2 1. 79 1, 100 54. 9 0. 725 10. 1 19. 0 61. 7 l2. 9 3. 2 96. 8 54. 1 36. 8 9.

A. Constant contact time seconds)variable temperature. B. Constant temperaturevariable contact time. I Bead cracking catalyst of 42 A. L-fresh dried (10.1 wt. percent AlnOa). Volume of catalyst 150 cc. b 2-Methylnapthalenc-nltraviolet absorption analysis indicated 99.4 percent purity. Eastman practical Z-methylnaphthalene. 4 Volume 2-methylnaphthalene charge at O./vol. catalyst/hour. I Based on total charge to reactor and assuming 150 cc. of voids.

1 Based on ratios of naphthalene, coke and gas.

by mass spectrometer, ultravlolet light spectrometer, dis- RUNS IN THE PRESENCE OF HYDROGEN EXAMPLES 23 THROUGH 31 RUNS IN THE ABSENCE OF ED MATERIALS A series of runs were made, 1n WhlCh Z-methylnaph- EXAMPLES 1 THROUGH 13 thalene was contacted with the s1l1ca-alum1na catalyst as A series of runs were made in which 2-methy1naph-. thalene was contacted with a silica-alumina catalyst, in the absence of hydrogen, and at a constant contact time of about 10 seconds. The catalyst was a bead-form silicaalumina catalyst containing about 10.1 per cent, by weight, of alumina, which was produced as described in EXAMPLES 32 THROUGH 34 Patent In these runs, the A series of runs were made, in which Z-methylnaphperature was varied to show the yields at Various t mthalene was contacted with the silica-alumina catalyst as peratures. Pertinent data and results for these runs are used in Examples 1 through 22, at various temperatures,

and under one atmosphere of hydrogen pressure. The

for these runs are set forth in part A of Table II.

used in Examples 1 through 22, at various contact times,

0 temperatures were varied to demonstrate the efiect of temperature on the yields of naphthalene. Pertinent data set forth in part A of Table I. for about 10 seconds contact time, and under about 20' atmospheres hydrogen pressure. These runs show the effect of temperature on yield of naphthalene, under the Series of were made the Same catalyst higher pressure conditions. Pertinent data and results as Examples 1 through l Qmethylnaphthalenfl for these runs are set forth inpart B of Table II.

The contact temperature was maintained at about 1000 F., while the contact times were at about 5 seconds. The EXAMPLES 35 AND 36 pertinent data and results for these runs are set forth Two runs were made, in which -2-methylnaphthalene in the first part of part B of Table I, along with data was contacted with the silica-alumina catalyst, as used EXAMPLES 14 THROUGH 18 in Examples lthrough 22., atv 1100 F-., under, oneatmosphere hydregen. pressure, and for contact times of: 19.8'

and 24.7 seconds, respectively. Pertinent data and) results for these runs are set forth in part C of Table 11, along with data and results for certain runs from part A thereof, in. order to show the effectof contact time on the yield of naphthalene.

EXAMPLES 37' Tnaouoa- 39 A series of runs were made, in which. Z-methylnaphthalene was, contacted with the silica-alumina catalyst as used in Examples 1 through 22, at 1000 F., under 40 atmospheres pressure, and. for. contact. times of about 10 seconds. Pertinent: data-1 andjrcsultsr for these runs areset forth in; Part. D. of; Table II. along. with. data and results for certain runs; from. parts A. and B thereof, in order to demonstrate. the efiect of; pressure on, the yield of naphthalenm.

EXAMPLES 40 AND 41 Table Il.Demethy[atin of methylnaphthalene over head catalyst [Hydrogen added to the charge] Charge Stock Hydrogen Added Pressure Length Methyl- Contact Example m... Mole L. a ra t es t G. G. Min. Moles Per Mole Atmos. m

I at S. T. P. Charge Gauge A. EFFECT OF TEMPERATURE (CONSTANT CONTACT. TIMES-ONEATMOSPHERE PRESSURE) B. EFFECT OF TEMPERATURE (CONSTANT CONTACT TIMESTWENTY'ATMOSPHERES PRESSURE) C. EFFECT OF CONTACT TIM-E (CONSTANT TEMPERATURES-ONE ATMOSPHERE PRESSURE) D. EFFECT" OF PRESSURE (CONSTANT CONTACT TIMES AND-TEMPERATURES) E. DEMETHYLATION OF 1-METHYLNAPHI1HALENE I Bead cracking catalyst 0142 A. L-lresh dried (10.1-wt. percentAI OR).

Volume-oi catalystcc.

b a methylnaphthalene Reilly (purified; ultra-violet analysis indicated 99.4% purity)-un.less otherwise indicated.

@ 2-n1ethylnaphthaleneEastman practical.

d Volume-2-rnethylnaphtha1ene charge at 50 C./vol. catalyst/hour.

a Based on total charge to reactor and assuming 150 cc. of voids.

1 Both yield per pass andultimate yield are expressed as weight percent of methylnaphthailenecharged.

ciBased'on ratios .otnaphthalem, coke and .gas. Liquid b0i1ing below 200C. Refractive index nn 1.49001.5200. i l-mthylnaphthalene.

Gas

Low Boilers Coke Yield of Products, -IUltimate Weight Percent Naphthalene 634. AMZ 55 Total f Gas Low Boilers [Hydrogen added to the charge] Coke 262 QLL 040 LLL Pertinent EXAMPLE 47 Yield of Products, Weight Percent Per Pass Residue data and results of this run are set forth in Table IH.

Example A. EFFECT OF TEMPERATURE (CONSTANT CONTACT TIMES-ONE ATMOSPHERE PRESSURE) B. EFFECT OF TEMPERATURE (CONSTANT CONTACT TIMES-TWENTY ATMOSPHERES PRESSURE) 0. EFFECT OF CONTACT TIME (CONSTANT TEMPERATURESONE ATMOSPHERE PRESSURE) 5 07 4 05287036 3 5687 33 430 4 0 5Jo 5 4 u m m m n n n m m S m E 8 3 m 2% T M 5 624 6 665 m wflwflma o w E T m m m 7 6650 A 65218828 A 31 5 8873 9 9999 S %%MW%M% M Wm E 1 H 1 m P T A 9 5 7 R-6 T 860623 m9 m 33 0 2244, w QuLLLL o Y 2L T H N m m 0 M C n u 1 m F m m A 0 n u m N W m N m w T E m 1 a m 9 9&&O. 6 4533 m NHW$WQWW M M R E P D M E 3 6029 73736934 35 1 @233 m mmmmmn an E F F E n n n n u 5 2 23 mu MATERIALS EXAMPLES 42 THROUGH 45 RUNS IN THE PRESENCE OF VARIOUS ADDED 0 time, and in the presence of added benzene.

A run was made, in which Z-methylnaphthalene was contacted with the silica-alumina catalyst as used in the preceding examples, at 1000 F., for a ten-second contact time, and in the presence of added cyclohexane. Pertinent data and results for this run are set forth in Table III.

A series of runs were made, in which 2-methylnaphthalene was contacted with the silica-alumina catalyst as used in the preceding examples, for ten-second contact times, at various temperatures, and in the presence of Pertinent data and results for these runs ar'eset forth in Table HI.

EXAMPLE 48 A run was made, in which Z-methylnaphthalene was contacted with the silica-alumina catalyst as used in the preceding examples, at 1000 F., for a ten-second contact time, and in the presence of added methylcyclohexane. Pertinent data and results for this run are set-forth in preceding examples, at 1000 F., for a ten-second contact 7 Table III.

added nitrogen gas under one atmosphere pressure.

EXAMPLE 46 A run was made, in which 2-methylnaphthalene was contacted with the silica-alumina catalyst as used in the ans-once Ill [Nitrogen or monocyclic hydrocarbonadded'to the charge] chargesmckb Yield ofProducts, -I'Weight' Perfl gig gf f'i' Moles/ Tam Length 53 E5 Contact cent? Pass --Percent g Example Type Moles Mole o of Run, Time,

Charge 15132/ .Mm. See N h R 1 N h in a ap es-' ap thalene due Coke Gas Total thalene Coke Gas 6. 98. 6 0.28 1, 000 358 0. 112 10. 0 15. 1. 75. 2 8. 1 1. O 99. 4 62:3 4:2 6. 0 Q8. 6 0.28 1, 000 358 0. 112 10. 0 l4. 0 74. 9 7.8 1. 0 97.7 61. 3 4.5 6. 0 98. 0. 26 1, 100 384 O. 104 10. 0 19. 4 58. 5 .15. 7 2. l 95. 7 52. 1 5. 7 6. 0 98. 6 0.26 1, 100 383 0. 105 10. 0 21. 1 51. 6 E20. 0 Z. 2 95.3 48; 3 6:10 1. O" 98. 6 0.?7 1, 000', 102 0:391 10. 0 13.9 77. 1 6* 1. 3 99.9 60;9 5:",8 1. 0 98. 6 0.96 1, 000 102 0.39] 1010 11. 9 79. 7 6.'2' 1. 1 h 9829 61: 9 52.8 1. 0 98. 4 0.08 1, 000 100 0.399 10. 0 11. 5 84. 2 5x6, 1. 1 i 192:4 "63. 2' 6.70

( Bead cracking catalyst of 42 A. I.Fresh dried (10.1 wt. percent A1203). Vol. of catalystl50 cc.

( 2methylnaPhthalene-mltraviolet analysistindicated 99.4 percent-.pmity.

Volume 2-methylnaphthalene charge at 50 O./vol. catalyst/hour. (#LBaserLontotal chargetoreactornnd assuming 150, cc. of voids.

( Both yield per pass and ultimate yield are expressed as weight percent of methylnapthalene charged.

( Basedon ratios'oi naphthalene, coke and gas.

( Unreacted benzenewas recovered as a product but is notlncludedin the yield in the table.

( Recovered hydrocarbon boiling in the cyclohexane rangeavas notaanalyzed.

Recovered monocyclic hydrocarbon analyzed by mass spectrometer. benzene, '51 percent toluene,1.0 percent methylcyolohexene,0.6 percent xylene,'0.3 percent propylbenzene. All analyses for naphthalene by ultraviolet absorption analysis of ZOO-235 C. fraction.

'From'thc preceding examples'takcn in conjunction with the figures, it will be apparent that the present process, using hydrogen gas, c'tfects superior yields of dcmthylated products. -It-will be'notcd, also, that the addition of an inert gas, such as nitrogen, for a diluent-has little effect on the yield. Likewise, the use of other materials such asZ-benzcne, cyclohexane, andmcthylcyclohexane, which are considered potential sources of hydrogen, have/no advantageous cflcct. It is onlyby the use of hydrogen that the advantages of the present process are achieved. In order to illustratethis, the dataior runsnsing various added materials are set forth in a summary in Table IV.

Table lV.-Demethylati0n of methylnaphthalene a [Cornparisonot efiects-oi added materials] e Bead catalyst, 42 A. 1.; 1,000 F.; second contact time.

The products produced by the process of this invention have many uses and applications well known to those familiar with the art. Thus, naphthalene is a well known larvicidc, and an intermediate for the production of phthalic anhydridclbyloxi'dation thereof. "Mc'thylphthalic anhydi'ides are producedfrom methylnaphthalenes.

Although the present invention lras been described with prcficrred embodiments, it is to be understood. that modifications-and variationscanbc resorted 1:0.W-ithout departing from. the spirit .andyscope-of this invcntion aszthose skilled. inrthc .art willreadily understand. Such variations and modifications are considcrcdtto ebc within the scope and purview of the appended claims.

What is claimed is:

11. A tproccss :for the .dcrncthylation 90f :mcthylnaphthlcncgwhich comprises contactingsa mcthylnaphthalcnev with re silicaealumina :cracking catalyst, rcontaining rhetwcenaabout'.5;pcrr.centland about ::perzccnt,Ebyrwveight, of aluminmaat :a temperature of ibetwccn; about 900 and about 1200" F., for a period of time of betweeniabout Mole percent composition: 82.1 percent methylcyclohexane, 10.9 percent one second and'about60 seconds, and in'the presence of hydrogen gas at-substantially atmospheric pressure.

2. A ,process for the demcthlyation of mcthylnaph- -thalenes, which comprises contacting-a-mcthylnaphthalcne witlra silica-alumina catalyst, containing between about 8 per cent and about lipcr cent, by weight, of alumina, at a temperature of between about'900 and about -1 F, for a period of time of between-about one-sec- 0nd and about 20 seconds, and in the presence of hydrogcn gas at substantially atmospheric pressure.

3. A continuous process for the demethylation of methylnaphthalenes, which comprises contacting a methyl- -naphthalene with a-silica-alumina catalyst, containing-be- .tweenabout 8--pcr ccntand about 15 per cent, bywcight, of alumina, at a temperature of between about 900F. .and about ll00 F., for a period of time of between-about one second arid-about 20 seconds, in thepresence of hydrogengas at substantially atmospheric pressure,-scpar.ating the 'demethylatcd methylnaphthalcnc from the undemethylated methylnaphthalenes, and recycling said undcmcthylatcd mcthylnaphthalenes.

4. A process for the production of naphthalene from a -rnonomethylnaphthalenc, which comprises contacting a monorncthylnapththalenc with a silica-alumina catalyst, -containing bctween' about-8'per-ccnt and-boutlS--pcrccnt, by .weight, of alumina, at .a temperature. of between about "900 F. and about 1l00F., for a period of time of'bc- 'twecn about one second and about"20 seconds, and in the presence of hydrogen gas at substantially atmospheric pressure.

5. A continuous process for the production of naphthalene-from amonomethylnaphthalene, which comprises contacting a monomethy-l-naph thalcnc with a silica-alumina catalyst, containing between about 8 per cent and about 15 per cent, by wcight,of -alumina, -at-a tempcraturc of betwecnabout 9.00 F. and about 1100 F., for a period of time ,of'bctwccn about one second and aboufZOsccends," in theprcscnce of hydrogen gas .at substantially atmospheric pressure, separating naphthalene from undemethylated inethylnaphthalencs, and recycling said undcmethylated mcthylnaphthalcncs.

6."The process for the production of naphthalcnc'from a monomethylnaphthalenc, which comprises contacting 2-mcthylnaphthalcne with a silica-alumina catalyst, c011- tainingebetwecnezabout:8;per;cent @andeabou 16- per". cen byrweight,:ofzalumina,:at.aztcmpcraturczfif bctweema-bont 900 *F. landzabout 1 100 .-F., -tor ra.-per i,od cfrtirnc;.of: be-

tween about one second and about 20 seconds, and in the presence of hydrogen gas at substantially atmospheric pressure.

7. A process for the production of naphthalene from a monomethylnaphthalene, which comprises contacting Z-methylnaphthalene with a bead-form silica-alumina catalyst, containing about 10 per cent, by weight, of alumina, at about 900 F. to 1100 F., for 10 seconds, and in the presence of hydrogen gas at substantially atmospheric pressure.

8. A process for the production of naphthalene from a monomethylnaphthalene, which comprises contacting l-methyluaphthalene with a silica-alumina catalyst, containing between about 8 per cent and about 15 per cent, by weight, of alumina, at a temperature of between about 900 F. and about 1lOO F., for a period of time of between about one second and about 20 seconds, and in the presence of hydrogen gas at substantially atmospheric pressure.

9. A process for the production of naphthalene from References Cited in the file of this patent UNITED STATES PATENTS 2,194,449 Sachanen et al Mar. 19, 1940 2,380,279 Welty July 10, 1945 2,384,942 Marisic Sept. 18, 1945 2,436,698 Oblad Feb. 24, 1948 OTHER REFERENCES Thomas et al.: Jour. Am. Chem. Soc., vol. 66, pages 1694-6, 3 pages (October 1944).

Sachanen (B), Conversion of Petroleum, 2nd edition,

0 page 88, New York (1948). 

1. A PROCESS FOR THE DEMETHYLATION OF METHYLNAPHTHALENES, WHICH COMPRISES CONTACTING A METHYLNAPHTHALENE WITH A SILICA-ALUMINA CRACKING CATALYST, CONTAINING BETWEEN ABOUT 5 PER CENT AND ABOUT 20 PER CENT, BY WEIGHT, OF ALUMINA, AT A TEMPERATURE OF BETWEEN ABOUT 900* F. AND ABOUT 1200* F., FOR A PERIOD OF TIME OF BETWEEN ABOUT ONE SECOND AND ABOUT 60 SECONDS, AND IN THE PRESENCE OF HYDROGEN GAS AT SUBSTANTIALLY ATMOSPHERIC PRESSURE. 